Exposure controlling apparatus

ABSTRACT

An exposure controlling apparatus includes a sensor for effecting photometry by separating light from an original picture into a plurality of separated components; a storage device for storing a value concerning the spectral sensitivity of the sensor and a value concerning the spectral sensitivity of a copying sensitive material to be copied; an estimating device for estimating a spectral characteristic of the original picture on the basis of a photometric value of the sensor and the value concerning the spectral sensitivity of the sensor stored in the storage device; and a controller for determining a synthetic value which is equivalent to a value measured by a sensor having a spectral sensitivity distribution identical with or similar to a spectral sensitivity distribution of the copying sensitive material on the basis of the spectral characteristics of the original picture estimated and the value concerning the spectral sensitivity of the copying sensitive material, and for controlling exposure amount on the basis of the synthetic value. Accordingly, it is possible to control exposure amount by estimating the spectral characteristics of the original picture even from photometric values obtained by effecting photometry by separating the light into components having a wide half-width.

BACKGROUND OF THE INVENTION

The present invention relates to an exposure controlling apparatus, andmore particularly to an exposure controlling apparatus for controllingthe exposure amount of an image copying apparatus such as an automaticphotographic printer for printing an image on a copying sensitivematerial from a color original picture, particularly on a color printpaper from a color film. Description of the Related Art:

In general, when a color image is reproduced on a copying sensitivematerial from a color original picture, exposure amount is determinedfor the respective colors of red (R), green (G), and blue (B) bymeasuring the integral transmittance (or reflection) density of the R, Gand B light by using a photometric device having color separationfilters constituted by dyed filters and deposited filters. In order todetermine exposure amount accurately, it is necessary to photometricallydetermine the exposure amount which actually contributes to thesensitization of the copying sensitive material. For this purpose, it isnecessary to make the spectral sensitivity distribution of thephotometric device coincide with the spectral sensitivity distributionof the copying sensitive material. The spectral sensitivity distributionof the copying sensitive material is asymmetrical about a wavelength atwhich sensitivity becomes maximum. With dyed filters and depositedfilters, however, in order to fabricate them in such a manner that thetransmittance distribution becomes asymmetrical, it is necessary tocombine a multiplicity of filters, so that it is difficult to massproduce them and also difficult to fabricate them with a high degree ofaccuracy.

Accordingly, in photo-resist exposure apparatus, a technique is known inwhich the spectral sensitivity distribution of a photometric device ismade to coincide with the spectral sensitivity distribution of a copyingsensitive material by separating the light from an original picture intospectral components and effecting processing by adding weight to theseparated components. Japanese Patent Laid-Open No. 88624/1983 disclosesa photo resist exposure apparatus in which the aforementioned processingis effected by using a diffraction grating, a convergent optical system,and a photo-detector. However, a complicated mechanism is required so asto ensure that spectral sensitivity characteristics will not change dueto the relative arrangement of these optical elements. Japanese PatentLaid-Open No. 95525/1986 discloses a photo resist exposure apparatus inwhich a multiplicity of interference filters are disposed instead of theaforementioned diffraction grating, the light transmitted through anoriginal picture is separated into spectral components, and processingis effected by adding weight to the separated components. However, sincethe multiplicity of interference filters are required, a problem existsin that in cases where the number of photometric wavelengths is large,it is difficult to mass produce the interference filters by maintainingthe spectral accuracy of the filters. Also, there is an additionalproblem in that since the separated components obtained from theinterference filters exhibit a broad spectral distribution, even if aweighting addition is merely effected, the accuracy would beinsufficient for the purpose of this application. In addition, withrespect to color photographic printers, Japanese Patent Laid-Open No.134353/1989 discloses a technique in which light from an originalpicture is subjected to spectral separation using a prism and adiffraction grating or a spectral filter, and an image of a part of acopy original is formed on a panel of a photoelectric sensor into theconfiguration of a slit. In this technique, different photometricpositions are represented by rows of the panel, while spectral lightcorresponding to the photometric positions is converted to electricsignals by columns of the panel. In this technique, the same problem asthe one described above is encountered since the diffraction grating orthe spectral filter is employed. Furthermore, since the light isseparated into a multiplicity of spectral components of light, there isa problem in that the quantity of each spectral component of light issmall, resulting in a shortage of the quantity of light. In addition,since the light is separated through diffraction by the use of theprism, there are drawbacks in that it is necessary to make the projectedlight into parallel light, that the apparatus becomes large in size,that the quantity of light decreases substantially since the light isseparated into both rows and columns, and that a large difference in thequantity of light results for each spectrum, thereby making itimpossible to effect photometry by using the same panel. Japanese PatentLaid-Open No. 142719/1989 also discloses the use of a prism or adiffraction grating, and a lens, and a two-dimensional array sensor.However, in this arrangement as well, the same drawbacks as thosedescribed above are encountered since the prism or the diffractiongrating is used.

In order to overcome the conventional drawback of the quantity of lightbecoming short, it suffices to effect photometry by using spectral lighthaving a wide half-width (e.g., 5-20 nm), or using light having greaterdiffusion than parallel light. Nevertheless, photometric values fail toexpress values measured by the spectral sensitivity distribution of thecopying sensitive material owing to the broadening of the range of thephotometric wavelengths.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstancesand has a primary object to provide a compact exposure controllingapparatus capable of being mass produced at low cost and of overcoming ashortage of the quantity of light by estimating the spectralcharacteristics of an original picture by conducting photometry afterseparating the light into spectral light having a wide half-width.

Another object of the present invention is to provide an exposurecontrolling apparatus capable of improving color correction performance.

Still another object of the present invention is to provide an exposurecontrolling apparatus having a photometric sensor exhibiting a spectralsensitivity distribution of high accuracy.

To attain the aforementioned objects, in accordance with the inventionthere is provided an exposure controlling apparatus comprising: a sensorfor effecting photometry by separating light from an original pictureinto a plurality of separated components; storage means for storing avalue concerning the spectral sensitivity of the sensor and a valueconcerning the spectral sensitivity of a copying sensitive material tobe copied; estimating means for estimating a spectral characteristic ofthe original picture on the basis of a photometric value of the sensorand the value concerning the spectral sensitivity of the sensor storedin the storage means; and controlling means for determining a syntheticvalue which is equivalent to a value measured by a sensor having aspectral sensitivity distribution identical with or similar to aspectral sensitivity distribution of the copying sensitive material onthe basis of the spectral characteristics of the original pictureestimated and the value concerning the spectral sensitivity of thecopying sensitive material, and for controlling exposure amount on thebasis of the synthetic value.

Adjacent ones of the plurality of separated components may havewavelength bands which overlap each other.

The sensor may have a wedge-shaped or stepped interference filter whichis provided with an interference film disposed on a transparentsubstrate and having varying thicknesses at different positions thereof,the interference filter being adapted to separate the light from theoriginal picture into a multiplicity of separated components.

It is effective if the sensor is arranged to effect photometry byseparating a wavelength band corresponding to a maximum sensitivitywavelength band of the copying sensitive material into a plurality ofseparated components.

In addition, the exposure controlling apparatus may comprise: a sensorfor effecting photometry by separating light from an original pictureinto a plurality of separated components; storage means for storingpeculiar values obtained by integrating spectral sensitivitydistributions of the sensor corresponding to the respective separatedcomponents over very fine wavelength sections including a centralwavelength of each of the separated components, and spectralsensitivities of a copying sensitive material corresponding to the verysmall wavelength sections; estimating means for estimating spectralcharacteristics of the original picture corresponding to the respectivevery small wavelength sections on the basis of photometric values of thesensor corresponding to the respective separated components and thepeculiar values stored in the storage means; and controlling means fordetermining a synthetic value which is equivalent to a value measured bya sensor having a spectral sensitivity distribution identical with orsimilar to a spectral sensitivity distribution of the copying sensitivematerial by integrating the product of the respective spectralcharacteristics of original picture estimated and the respectivespectral sensitivities of the copying sensitive material, and forcontrolling exposure amount on the basis of the synthetic value.

Referring now to FIGS. 7A to 7C, a description will be given of thebasic principle of the present invention. As shown in FIG. 7A, it isassumed that a spectral characteristic curve based on actualmeasurements obtained when an original picture was photometricallymeasured by separating the light from the original picture into threeseparated components by using sensors arranged as shown in FIG. 7B isexpressed by f₁ (λ) and that a true spectral characteristic curve isexpressed by f₂ (λ). The spectral characteristics referred to hereinmean a spectral transmittance distribution, a spectral reflectancedistribution, a spectral density distribution, and a spectral reflectiondensity distribution, or characteristics and values correspondingthereto. It should be noted that S.sub.λ1, S.sub.λ2, S.sub.λ3 in FIG. 7Bshow respective spectral sensitivity distributions of sensors S₁, S₂,S₃. Since the spectral characteristics of an original picture (i.e.,film color matter) exhibit a gentle distribution curve, it is possibleto estimate them with a small number of wavelengths. Accordingly,dividing points are determined as λ₀ <λ₁ <λ.sub. 2 <λ₃ in such a mannerthat λ₁ becomes an intermediate wavelength between the centralwavelengths of S.sub.λ1 and S.sub.λ3, λ₂ becomes an intermediatewavelength between S.sub.λ2 and S.sub.λ3, λ₀ is selected so that thecentral wavelength of S.sub.λ1 is located at a mid-point between λ₀ andλ₁, and λ₃ is selected so that the central wavelength of S.sub.λ3 islocated at a mid-point between λ₂ and λ₃. The spectral sensitivitydistribution of each sensor is divided into small sections [λ₀, λ₁ ],[λ₁, λ₂ ], and [λ₂, λ₃ ] and it is assumed that, for instance, spectralcharacteristics a-b of the original picture are approximated by c-d. Itis assumed that true values at the central wavelengths within the smallsections are T₁, T₂, and T₃, actual measurements are F₁, F₂, and F₃, andthe spectral sensitivity distributions of the sensor are S.sub.λ1,S.sub.λ1, and S.sub.λ3 . In addition, it is assumed that the spectralsensitivity distribution of the copying sensitive material is expressedby FIG. 7C, and the spectral sensitivities of the copying sensitivematerial at the central wavelength of each sensor are P₁, P₂, and P₃.The actual measurement F₂ in the small section [λ₁, λ₂ ] can beexpressed by using true values and the spectral sensitivitydistributions of respective regions of the sensor, as follows: ##EQU1##

It should be noted that actual measurements F₁, F₂ can also be obtainedin a similar manner as described above.

The above Formula (1) can be generally expressed as follows: ##EQU2##where j is a number allotted in correspondence with a wavelength, andj=1, 2, 3, ..., or n, and i is a number allotted in correspondence witha peak value of the spectral sensitivity of the sensor, i.e., a numberallotted in correspondence with each region of the sensor, and in theabove-described case, i=1, 2, or 3.

If a generalization is made under the assumption that there are nregions of the sensor, and the light is separated into n separatedcomponents so as to effect photometry, the following formula can beobtained: ##EQU3##

If the spectral sensitivity distributions of the sensor are have alreadybeen measured in advance, the spectral sensitivity S.sub.λi within anarbitrary section [j-1, j] can be determined in advance, so that##EQU4## in Formula (3) above becomes a predetermined value peculiar tothe sensor. If this peculiar value is set as Sij, the relationship amongthe true value, the actual measurement, and the peculiar value can beexpressed as matrix as follows: ##EQU5##

Accordingly, if an inverse matrix of S is expressed by S⁻¹, a true T canbe expressed by S⁻¹ ·F.

A photometric value measured by a sensor having the same spectralsensitivity distribution as the sensitivity distribution of the copyingsensitive material, i.e., a synthetic value Tp, can be expressed asfollows: ##EQU6## where K=ΣΔPi/n, and ΔPi is a wavelength width λ_(j)-λ_(j-1) at an arbitrary section [j-1, j].

Accordingly, it is possible to estimate the spectral characteristics ofan original picture on the basis of the photometric values F1, F2, ...at a time when photometry is effected by separating the light from theoriginal picture into a plurality of separated components, and also onthe basis of spectral sensitivity distributions S.sub.λ1, S.sub.λ2, ...corresponding to the separated components of the sensor. In addition, itis also possible to obtain a photometric value which is equivalent to avalue measured by a sensor having a spectral sensitivity distributionidentical with or similar to the spectral sensitivity distribution ofthe copying sensitive material on the basis of the spectralcharacteristics of the original picture estimated and the spectralcharacteristic distribution of the copying sensitive material.

To this end, in accordance with the present invention, values concerningthe spectral sensitivity of the sensor and values concerning thespectral sensitivity of the copying sensitive material are stored inadvance in the storage means, and photometry is effected by the sensorby separating the light from the original picture into a plurality ofseparated components. The estimating means estimates the spectralcharacteristics of the original picture on the basis of the photometricvalues of the sensor and the values concerning the spectral sensitivityof the sensor, as described above. Then, the controlling meansdetermines a synthetic value which is equivalent to a value measured bya sensor having a spectral sensitivity distribution identical with orsimilar to the spectral sensitivity distribution of the copyingsensitive material, as described above, on the basis of the spectralcharacteristics of the original picture estimated and the valuesconcerning the spectral sensitivity of the copying sensitive material.The controlling means controls exposure amount on the basis of thissynthetic value.

Here, the values concerning the spectral sensitivity of the sensorinclude the spectral sensitivity distribution of the sensor or a valuecorresponding thereto, a value concerning the spectral sensitivity ofthe copying sensitive material, the spectral sensitivity distribution ofthe copying sensitive material, or a value corresponding thereto.

To separate the light from the original picture into a plurality ofseparated components, it suffices to use an interference filter havingan interference film which is disposed on a transparent substrate andhas varying thicknesses at different positions thereof. The interferencefilter having the interference film can be readily formed bycontinuously changing the thickness into the configuration of a wedge ordiscontinuously changing the thickness in the form of steps. Inaddition, by interposing a film having a low refractive index (MgF₂,cryolite, or the like) between two sheets of Ag film, one spectralcomponent ranging from a visible range to a near infrared range can betransmitted through the interference filter depending on the thicknessof this film having a low refractive index. If the interference filterhaving an interference film which is disposed on a transparent substrateand has varying thicknesses at different positions thereof is disposedon a photovoltaic effect type optical sensor such as a MOS, CCD, or thelike (hereinafter referred to as the sensor, area sensor, or linesensor), it is possible to photometrically measure a multiplicity ofspectral components corresponding to the thickness of the interferencefilm. Accordingly, as compared with a case where a plurality ofinterference filters having different central wavelengths are combinedas in the prior art, the interference filters can be produced at lowcost. In addition, since the light is separated by making use ofinterference, the interference filters can be made compact as comparedwith prisms for separating the light by making use of refraction. Withsuch interference filters, since the incident light is separated into amultiplicity of spectral components, it is possible to compensate for ashortage of the quantity of light if a plurality of spectral componentsin predetermined wavelength bands corresponding to the half-widths ofthe separated components.

As for the spectral sensitivity distributions of copying sensitivematerials, particularly photographic color print papers, theconfigurations of the spectral sensitivity distributions are similareven if the manufacturers, their types, and the like are different.Hence, maximum values of the spectral sensitivities of various colorpapers exist substantially in an identical wavelength band. Accordingly,if photometry is effected by separating the wavelength bandcorresponding to that maximum sensitivity wavelength band into at leasttwo, preferably not less than two, separated components, it is possibleto easily obtain a synthetic value which is equivalent to a valuemeasured by a sensor having a spectral sensitivity distributionidentical with or similar to the spectral sensitivity distribution ofone of various copying sensitive materials, particularly various colorprint papers.

The maximum spectral sensitivities of various color papers exist in the450-485 nm wavelength band, the 450-560 nm wavelength band, and the680-710 nm wavelength band, i.e., in the wavelength bands of the threeprimary colors. Therefore, it is preferable to effect photometry byseparating each of these wavelength bands into a plurality of separatedcomponents by using the sensor.

In order to separate a wavelength band corresponding to the maximumsensitivity wavelength band into a plurality of separated components, itsuffices to use a filter on which an interference film for separatingthe relevant wavelength band into these separated components is deposedat different positions in an identical plane. In this case, as for thespectrally separating filter, it is possible to use filters that arefabricated for the respective separated components, or it is possible touse a single filter on which all the necessary interference films suchas those described above are deposited. In addition, it is possible touse three filters divided for the primary colors of R, G, and B.Furthermore, it is possible to use a filter having a first interferencefilm for separating the light into components having narrow half-widthsand a second interference film for separating the light into componentshaving wider half-widths than the above. This arrangement is adopted toeffect photometry at high accuracy using narrower intervals with respectto components having narrow half-widths, since the ratio of contributionof a photometric value to exposure amount is large with respect to thewavelength band corresponding to the maximum sensitivity wavelengthband, and to effect photometry by using wider intervals with respect tocomponents having wider half-widths than the above, since the ratio ofcontribution of a photometric value to exposure amount is small withrespect to the wavelength band other than the one corresponding to themaximum sensitivity wavelength band. Since the number of separatedcomponents obtained is reduced by the use of the above-described filter,this filter can be readily mass produced by using a masking method inwhich deposition is carried out consecutively by making its portionsother than the portion where the interference film is deposited.

In order to estimate the spectral characteristics of the originalpicture, it is necessary to determine a value peculiar to the sensor onthe basis of the spectral sensitivity distribution of the sensor, apeculiar value in which spectral sensitivity distributions of the sensorcorresponding to the respect separated components are integrated oververy small wavelength sections including the central wavelengths of theseparated components may be stored in the storage means instead of thespectral sensitivity distributions of the sensor. In this case, spectralcharacteristics of the original picture corresponding to the respectivevery small wavelength sections are estimated on the basis of peculiarvalues and photometric values of the sensor corresponding to therespective separated components. Then, a synthetic value which isequivalent to a value measured by a sensor having a spectral sensitivitydistribution identical with or similar to a spectral sensitivitydistribution of the copying sensitive material is determined byintegrating the product of the respective spectral characteristics oforiginal picture estimated and the respective spectral sensitivities ofthe copying sensitive material.

As described above, in accordance with the present invention, exposureamount can be controlled by estimating the spectral characteristics ofthe original picture even on the basis of photometric values obtained byseparating the light into separated components having large half-widths.Hence, it is possible to obtain an advantage in that it is possible toprovide a compact exposure controlling apparatus which does not cause ashortage of the quantity of light and is capable of being mass producedwith high accuracy and at low cost.

In accordance with one aspect of the present invention, as shown in FIG.17, the exposure controlling apparatus comprises: a first sensor A foreffecting photometry by separating light from an original picture into amultiplicity of spectral components or a multiplicity of separatedcomponents and adapted to output a multiplicity of first photometricvalues corresponding to the multiplicity of spectral components and themultiplicity of separated separated components; a second sensor B havingmaximum sensitivities in wavelength bands corresponding to threesensitivity bands of a copying sensitive material, and effectingphotometry by dividing the original picture into a multiplicity offragments, the second sensor being adapted to output a multiplicity ofsecond photometric values corresponding the multiplicity of fragments;first calculating means C for calculating a first average image densitysynthesized by adding weight to each of the multiplicity of firstphotometric values; second calculating means D for calculating a secondaverage image density by averaging the multiplicity of secondphotometric values; third calculating means E for calculating a thirdaverage image density by averaging the second photometric valuesbelonging to a region whose color ratio or color difference from areference value on predetermined color coordinates is small; andcontrolling means F for calculating an exposure amount control value onthe basis of the first average image density, the second average imagedensity, and the third average image density, and for controlling theexposure amount on the basis of the exposure amount control value.

The first calculating means may calculate the basic exposure value onthe basis of the first average image density obtained by integrating ortotalizing k.sub.λ ·SP.sub.λ ·d.sub.λ over a predetermined wavelengthband where SP.sub.λ is a first photometric value at a wavelength λ ofone of the spectral components or one of the separated components,k.sub.λ is weight at the wavelength λ to be added to the firstphotometric value, and d.sub.λ is a wavelength width of one of thespectral components or one of the separated components.

The second average image density may be a density determined from anarithmetic average value of the multiplicity of second photometricvalues.

Furthermore, if it is assumed that the first average image density isPD1j, the second average image density is PD2j, and the third averageimage density is PD3j, the exposure controlling means may calculate theexposure amount control value in accordance with PD1j+F·f(PD3j, PD2j)where j is 1 to 3, respectively representing the three sensitivitywavelength bands of the copying sensitive material, F is a constant or avalue expressed by a constant, and f(PD3j, PD2j) is a functionalexpression comprising the third average image density PD3j and thesecond average image density PD2j.

In the above formula, an arrangement may be provided such that ##EQU7##

Referring now to FIG. 17, a description will be given of the operationin accordance with this first aspect of the invention. The first sensorA photometrically measures the original picture by separating the lighttherefrom into a multiplicity of spectral components or a multiplicityof separated components, and outputs a multiplicity of first photometricvalues SP.sub.λ corresponding to the multiplicity of spectral componentsor the multiplicity of separated components. Here, λ is a numberspecifying a specific spectral component or separated component.SP.sub.λ represents a photometric value at the wavelength number λ. Inaddition, the second sensor B has maximum sensitivities in wavelengthbands corresponding to three sensitivity wavelength bands of the copyingsensitive material, photometrically measures the original picture bydividing it into a multiplicity of segments, and outputs a multiplicityof second photometric values ti corresponding to the multiplicity ofsegments. This ti represents a photometric value at an i-th fragment.The three sensitivity wavelength bands of the copying sensitive materialordinarily exist in the wavelength bands of red (R) light, green (G)light, and blue (B) light, but wavelength bands other than the above maybe used. The first calculating means C calculates a first average imagedensity (synthetic value) synthesized by adding weight k.sub.λ to eachof the multiplicity of first photometric values SP.sub.λ. This value isobtained by integrating or totalizing k.sub.λ ·SP.sub.λ ·d.sub.λ (whered.sub.λ is a wavelength width of one of the spectral components or oneof the separated components) over a predetermined wavelength band, e.g.,wavelength bands corresponding to the three sensitivity wavelength bandsof the copying sensitive material. In cases where the first averageimage density PDlj (where j is one of the three sensitivity wavelengthbands of the copying sensitive material, e.g., one of R, G, and B) isdetermined by addition, this value can be used as a large areatransmission density (LATD) which is given by the following formula:##EQU8## where λmin is a minimum value of the adding section, λmax is amaximum value thereof, and KA is a constant determined by calibrationand is used to adjust to a fixed density (e.g., 0) a photometric valueobtained by photometrically measuring a reference film (e.g., a filmbase portion) or a photometric value measured with no film. This firstaverage image density is used for determining a basic exposure amount.

The second calculating means D calculates a second average image densityby averaging the multiplicity of second photometric values PD2j. As forthis second photometric value PD2j, it is possible to use, for instance,LATD given by the following formula, i.e., a logarithm of an arithmeticaverage of the second photometric values: ##EQU9## where n is the numberof divisions, and KB is a constant which is determined by calibration inthe same way as described above.

The third calculating means E calculates a third average image densityby averaging (e.g., arithmetically averaging) the second photometricvalues belonging to a region whose color ratio or color difference froma reference value on predetermined color coordinates is small. As thesecolor coordinates, it is possible to use two- or three-dimensional colorcoordinates having as their coordinate axis one color or a combinationof two or more colors of the three primaries (e.g., Dx-Dy,Dx/(Dx+Dy+Dz), aDx+bDy+cDz, Dx/K, etc., where x, y, and z respectivelyrepresent a mutually different one color selected from among R, G, andB, and a, b, c, and K are constants). In addition, as a reference value,it is possible to adopt such as a value concerning a specific color ofthe original image, a value obtained from an average value of amultiplicity of images, a minimum value of photometric data, a valueobtained from photometric data on a specific image, a predeterminedspecific constant, and so forth. Furthermore, the reference value may bea value given by a functional expression or a table. In this case, thefunctional expression or table may be such that a reference valuechanges depending on, for instance, an image density. It should be notesthat as a specific color of the original image, a neutral color, a colorof skin, or a color determined from an average value of a multiplicityof images. Each of the second photometric data is converted to a pointon the aforementioned color coordinates by calculation, the secondphotometric values belonging to a region whose color ratio or colordifference from the reference value is small are selected, and theselected second photometric values are averaged, thereby calculating thethird average image densities PD3j. Thus, it is possible to prevent theoccurrence of color failures if the second photometric values belongingto a region whose color difference or color ratio from the referencevalue is small, i.e., a neutral color region or a region with a lowdegree of saturation, are used for determination of the exposurecontrol, which will be described below.

The controlling means F calculates an exposure amount control value E onthe basis of the first average image density PDlj, the second averageimage density PD2j, and the third average image density PD3j, andcontrols the exposure amount of the copying apparatus on the basis ofthat exposure amount control value. This exposure control value formula:

    Ej=PD1j+F·f(PD3j, PD2j)                           (14)

where F is a constant (e.g., 1.0) or a value expressed by a function).The first average image density PDlj is used for determining the basicexposure amount, while F·f(PD3j, PD2j) functions as an exposure amountcorrection value with respect to the basic exposure amount.

The correction value f(PD3j, PD2j) is a functional expression consistingof PD3j and PD2j, and is specifically given, for instance, by thefollowing formula: ##EQU10## where PD3j-PD2j is a color differencebetween two average image densities, while ##EQU11## is a term forcorrecting the two average image densities.

As described above, in accordance with the one aspect of the invention,since the basic exposure amount is determined on the basis of the firstphotometric values that are obtained through photometry by dividing thelight into a multiplicity of spectral components or separated light andhave spectrally high accuracy, the performance of correcting differencesin characteristics due to a difference in the film type can be improved.In addition, since the basic exposure amount is corrected by estimatingthe color of the object, it is possible to obtain the advantage thatcorrection corresponding to the contents of the image, i.e., thecorrection of color failures, can be effected without undermining thefilm type-correcting performance. In addition, since the basic exposureamount is determined by synthesizing the first photometric values, anadvantage can be obtained in that it is possible to overcome a shortageof the sensitivity of the sensor at a time when the light is separatedinto the multiplicity of spectral components or separated components.

In accordance with a second aspect of the invention, the exposurecontrolling apparatus comprises: a first sensor for effecting photometryby separating light from an original picture into a multiplicity ofspectral components, the first sensor including an interference filterwhich is provided with an interference film disposed on a transparentsubstrate and having varying thicknesses at different positions thereof,the interference filter being adapted to separate the light from theoriginal picture into the multiplicity of components having centralwavelengths corresponding to the thicknesses of the interference film; asecond sensor for photometrically measuring red, green, and blue lightby dividing the original picture into a multiplicity of fragments; andcontrolling means for determining a basic exposure amount on the basisof a synthetic value determined at least from spectral photometricvalues of the first sensor, and for controlling an exposure amount onthe basis of the basic exposure amount.

The controlling means in this aspect of the invention may determine thebasic exposure amount on the basis of the synthetic value determinedfrom the spectral photometric values of the first sensor, or determinethe basic exposure amount on the basis of a color control valuedetermined on the basis of the synthetic value determined from thespectral photometric values of the first sensor and of a density controlvalue determined on the basis of photometric values of the secondsensor, and control the exposure amount on the basis of the basicexposure amount.

The controlling means may further determine a correction valuecorresponding to the contents of an image of the original picture on thebasis of the photometric values of the second sensor, and control theexposure amount by means of a value in which the basic exposure amountis corrected by the correction value.

It is preferred that the first sensor is provided with a transmittedlight quantity controlling layer, or a pixel area of the first sensor ischanged, whereby the sensitivity of the first sensor to a long wave bandis lowered relative to its sensitivity to a short wave band. Inaddition, at that juncture, the first sensor is preferably arranged tolower the sensitivity with respect to a 500-600 nm wavelength band to1/2 to 1/5, and the sensitivity with respect to a 600 750 nm wavelengthband to 1/4 to 1/20.

In this second aspect of the invention, the first sensor has aninterference filter which is provided with an interference film disposedon a transparent substrate and having varying thicknesses at differentpositions thereof, the interference filter being adapted to separate thelight from the original picture into the multiplicity of componentshaving central wavelengths corresponding to the thicknesses of theinterference film. The interference filter having the interference filmcan be readily formed by continuously changing the thickness into theconfiguration of a wedge or discontinuously changing the thickness inthe form of steps. In addition, by interposing a film having a lowrefractive index (MgF₂, cryolite, or the like) between two sheets of Agfilm, one spectral component ranging from a visible range to a nearinfrared range can be transmitted through the interference filterdepending on the thickness of this film having a low refractive index.If the interference filter having an interference film disposed on atransparent substrate and having varying thicknesses at differentpositions thereof is disposed on a photovoltaic effect-type opticalsensor such as a MOS, CCD, or the like (hereinafter referred to as thesensor, area sensor, or line sensor), it is possible to photometricallymeasure a multiplicity of spectral components corresponding to thethickness of the interference film. Accordingly, as compared with a casewhere a plurality of interference filters having different centralwavelengths are combined as in the prior art, the interference filterscan be produced at low cost. Then, the first sensor photometricallymeasures the original picture by separating the light transmittedtherethrough or the light reflected therefrom into multiplicity ofspectral components. Weight which is determined in correspondence withthe relative spectral sensitivity distribution of the copying sensitivematerial is added to the spectral photometric values of the firstsensor. Thus, by adding weight to the spectral photometric values, it ispossible to make the spectral sensitivity distribution of the firstsensor and the spectral sensitivity distribution of the copyingsensitive material agree with each other. Accordingly, the controllingmeans is capable of determining the basic exposure amount on the basisof the photometric values of the first sensor and of controlling theexposure amount by using this basic exposure amount.

The second sensor effects photometry with respect to R, G, and B lightby dividing the original picture into a multiplicity of fragments. Sincethe first sensor effects photometry by dividing the light into amultiplicity of spectral components, it is possible to determine a colorcontrol value on the basis of a synthetic value determined from thespectral photometric values of the first sensor. The spectralsensitivity distribution of the second sensor is not necessarily agreeaccurately with the spectral sensitivity distribution of the copyingsensitive material. For this reason, an arrangement may be provided suchthat the basic exposure amount is determined on the basis of a colorcontrol value determined from a synthetic value determined from thespectral photometric values of the first sensor and a density controlvalue determined from the photometric values of the second sensor.

In addition, since the second sensor effects photometry by dividing theoriginal picture into a multiplicity of fragments, it is possible todetermine a correction value corresponding to the contents of the imageof the original picture by performing predetermined calculation on thebasis of a characteristic amount of the image obtained from thephotometric values (it is possible to use the techniques disclosed inJapanese Patent Laid-Open Nos. 28131/1979, 38410/1980, and 3133/1986)and by selecting necessary photometric values (it is possible to use thetechniques disclosed in Japanese Patent Laid-Open Nos. 189457/1987 and198144/1986), and the aforementioned basic exposure amount may becorrected with a correction value.

The lamps that are ordinarily used as exposing light sources emit asmall quantity of light in the short wave band, and the sensors alsoexhibit low sensitivity to the short wave band. Accordingly, when ahalogen lamp is used as a light source, it is necessary to lower thesensitivity of the first sensor with respect to the long wave bandrelative to its sensitivity to the short wave band. In order to alterthe sensitivity, it suffices to provide a transmitted light-quantitycontrolling layer (interference film or filter) or use a sensitivitylowering means for changing the pixel area of the sensor. Specifically,to lower the sensitivity, it suffices to lower the sensitivity withrespect to a 500-600 nm wavelength band to 1/2 to 1/5, and thesensitivity with respect to a 600-750 nm wavelength band to 1/4 to 1/20.

Thus, in accordance with the second aspect of the invention, since aninterference filter which is provided with an interference film disposedon a transparent substrate and having varying thicknesses at differentpositions thereof is used, advantages can be obtained in that massproduction is facilitated as compared with the case where a multiplicityof interference filters having different central wavelengths arecombined, and in that, in in coping with a change in the spectralsensitivity distribution due to the change of the copying sensitivematerial, it suffices to merely change the weight value of spectralphotometric values without needing to replace the filter. Furthermore,the present invention offers an advantage in that the apparatus can bemade compact and produced at low cost since no prism is used.

In addition, in accordance with this aspect of the invention, it ispossible to obtain an advantage in that a sufficient quantity of lightcan be secured if the sensitivity is changed in correspondence with awavelength band.

Furthermore, in accordance with this aspect of the invention, since thebasic exposure amount based on the average density of the picture isdetermined by the first sensor, and the exposure correction amount isdetermined by photometrically measuring the light from the picture bydividing the picture into a multiplicity of fragments, the spectralsensitivity distribution of the second sensor need not necessarily bemade to coincide with the spectral sensitivity distribution of thecopying sensitive material.

In addition, in accordance with a third aspect of the invention, theexposure controlling apparatus comprises: a first sensor forphotometrically measuring an original picture by separating a wavelengthband, corresponding to a maximum sensitivity wavelength band of acopying sensitive material for copying an image of the original picturethereon, into a multiplicity of separated components; a second sensorfor photometrically measuring red, green, and blue light by dividing theoriginal picture into a multiplicity of fragments; calculating means forcalculating a synthetic value which is equivalent to a value measured bya sensor having a spectral sensitivity distribution identical with orsimilar to a spectral sensitivity distribution of the copying sensitivematerial for copying by adding weight to photometric values of the firstsensor; and controlling means for determining a basic exposure amount onthe basis of at least the synthetic value determined by the calculatingmeans, and for controlling an exposure amount on the basis of the basicexposure amount. This control means may be arranged to calculate thebasic exposure amount on the basis of the synthetic value determined bythe calculating means, or determine the basic exposure amount on thebasis of a color control value determined from the synthetic valuedetermined by the calculating means and also on the basis of a densitycontrol value determined from photometric values of the second sensor,and control an exposure amount on the basis of the basic exposureamount.

The wavelength band corresponding to the maximum sensitivity wavelengthband preferably includes a 450-485 nm wavelength band, a 540-560 nmwavelength band, and a 680-710 nm wavelength band.

The first sensor may comprise a filter on which an interference film forseparating a wavelength band corresponding to at least one maximumsensitivity wavelength band into a plurality of separated components isdeposited at different positions in an identical plane.

In addition, the first sensor may comprise a filter on which aredeposited a first interference film for separating a wavelength bandcorresponding to a maximum sensitivity wavelength band into a pluralityof separated components and a second interference film for separating awavelength band other than the wavelength band corresponding to themaximum sensitivity wavelength band into a plurality of separatedcomponents having a half-width wider than that of the first interferencefilm.

The first sensor may comprise a filter on which are deposited a firstinterference film for separating a wavelength band corresponding to amaximum sensitivity wavelength band into a plurality of separatedcomponents at at intervals of a narrow wavelength and a secondinterference film for separating a wavelength band other than thewavelength band corresponding to the maximum sensitivity wavelength bandinto a plurality of separated components at intervals of a widerwavelength than the intervals of the wavelength.

In the third aspect of the invention, the first sensor photometricallymeasures the original picture by separating a wavelength band,corresponding to a maximum sensitivity wavelength band of the copyingsensitive material for copying an image of the original picture thereon,into a multiplicity of separated components. As for the spectralsensitivity distributions of copying sensitive materials, particularlyphotographic color print papers, the configurations of the spectralsensitivity distributions are similar even if the manufacturers, theirtypes, and the like are different. Hence, maximum values of the spectralsensitivities of various color papers exist substantially in anidentical wavelength band. Accordingly, if photometry is effected byseparating the wavelength band corresponding to that maximum sensitivitywavelength band into at least two, preferably not less than two,separated components, and weight is added to each of the photometricvalues, then it is possible to easily obtain a synthetic value which isequivalent to a value measured by a sensor having a spectral sensitivitydistribution identical with or similar to the spectral sensitivitydistribution of one of various copying sensitive materials, particularlyvarious color print papers. As for this weight, it is possible to use avalue obtained from the spectral sensitivity distribution or the like ofthe sensor. Even if the spectral sensitivity distribution of the firstsensor is offset from the spectral sensitivity distribution of thecopying sensitive material, it is possible to obtain the aforementionedsynthetic value by changing the weight. For this reason, the calculatingmeans adds weight to the photometric values of the first sensor, tothereby calculate a synthetic value which is equivalent to a valuemeasured by a sensor having a spectral sensitivity distributionidentical with or similar to a spectral sensitivity distribution of thecopying sensitive material.

Thus, by adding weight to the photometric values of the first sensor,the spectral sensitivity distribution of the first sensor can be made toagree with or approximate the spectral sensitivity distribution of thecopying sensitive material, so that the controlling is capable ofdetermining the basic exposure amount on the basis of at least thesynthetic value determined by the calculating means, and controlling theexposure amount on the basis of this basic exposure amount.

The second sensor effects photometry with respect to R, G, and B lightby dividing the original picture into a multiplicity of fragments. Sincethe first sensor effects photometry by separating the light into aplurality of separated components, the first sensor is capable ofdetermining a color control value on the basis of the synthetic valuedetermined by the calculating means. The spectral sensitivitydistribution of the second sensor need not necessarily agree accuratelywith the spectral sensitivity distribution of the copying sensitivematerial. For this reason, the basic exposure amount may be determinedon the basis of the color control value determined from the syntheticvalue obtained from the photometric values of the first sensor and alsoon the basis of the density control value determined from thephotometric values of the second sensor.

Furthermore, since the second sensor effects photometry by dividing theoriginal picture into a multiplicity of fragments, it is possible todetermine a correction value corresponding to the contents of the imageof the original picture by performing predetermined calculation on thebasis of a characteristic amount of the image obtained from thephotometric values (it is possible to use the techniques disclosed inJapanese Patent Laid-Open Nos. 28131/1979, 38410/1980, and 3133/1986)and by selecting necessary photometric values (it is possible to use thetechniques disclosed in Japanese Patent Laid-Open Nos. 189457/1987 and198144/1986), and the aforementioned basic exposure amount may becorrected with a correction value.

The maximum spectral sensitivities of various color papers exist in the450-485 nm wavelength band, the 540-560 nm wavelength band, and the680-710 nm wavelength band, i.e., in the wavelength bands of the threeprimary colors. Therefore, it is preferable to effect photometry byseparating each of these wavelength bands into a plurality of separatedcomponents by using the first sensor.

In order to separate a maximum sensitivity wavelength band into aplurality of separated components, it suffices to use a filter on whichan interference film for separating the relevant wavelength band intothese separated components is deposed at different positions in anidentical plane. In this case, as for the spectrally separating filter,it is possible to use filters that are fabricated for the respectiveseparated components, or it is possible to use a single filter in whichall the necessary interference films are deposited on a singlesubstrate. Furthermore, it is possible to use a filter having a firstinterference film for separating the light into components having narrowhalf-widths and a second interference film for separating the light intocomponents having wider half-widths than the above. This arrangement isadopted to effect photometry at high accuracy using narrower intervalswith respect to components having narrow half widths, since the ratio ofcontribution of a photometric value to exposure amount is large withrespect to the wavelength band corresponding to the maximum sensitivitywavelength band, and is also adopted to effect photometry by using widerintervals with respect to components having wider half-widths than theabove, since the ratio of contribution of a photometric value toexposure amount is small with respect to the wavelength band other thanthe one corresponding to the maximum sensitivity wavelength band. Sincethe filters used for the first sensor effect photometry with highaccuracy only with respect to necessary wavelength bands, and the numberof separated components is thereby reduced, this filter can be readilymass produced by using a masking method in which deposition is carriedout consecutively by making its portions other than the portion wherethe interference film is deposited.

As described above, in accordance with the third aspect of theinvention, wavelength bands corresponding to the maximum sensitivitywavelength bands of the copying sensitive material are separated into aplurality of separated components so as to effect photometry with highaccuracy. As a result, it is possible to obtain an advantage in that thenumber of separated components can be reduced as compared with the priorart, thereby making it unnecessary to use a special filter, prism or thelike for separating the light into a multiplicity of spectralcomponents, and making it possible to provide a compact exposurecontrolling apparatus capable of being easily mass produced at low cost.In addition, weight is added to the photometric values of the firstsensor so as to obtain photometric values which are equivalent to thosemeasured by a sensor having a spectral sensitivity distributionidentical with or similar to a spectral sensitivity distribution of thecopying sensitive material. Accordingly, an advantage can be obtained inthat alteration of the weight prevents the degree of agreement ofspectral sensitivity distributions and the versatility of the apparatusfrom being lowered, and makes it possible to cope with variations inproduction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically illustrating an embodiment of a colorphotographic printer to which the present invention is applicable;

FIGS. 2A to 2D are plan views illustrating filters used in a sensor inaccordance with this embodiment;

FIGS. 3A to 3C are diagrams respectively illustrating the spectraltransmittance distribution of the sensors shown in FIGS. 2A to 2C;

FIG. 4 is a plan view illustrating a state in which the filters aremounted;

FIG. 5 is a plan view illustrating another example in which the filtersare mounted;

FIGS. 6A to 6C are plan views illustrating examples of arrangement ofone of the filters used in the sensor of this embodiment;

FIGS. 7A to 7C are diagrams illustrating the basic principle ofcalculating a synthetic value;

FIG. 8 is a flowchart illustrating a routine of calculation inaccordance with the aforementioned embodiment;

FIGS. 9A and 9B are diagrams illustrating another example of calculatinga synthetic value;

FIGS. 10 to 15 are diagrams illustrating other examples of a firstsensor;

FIG. 16 is a flowchart illustrating a routine for calculating exposureamount in accordance with a second embodiment;

FIG. 17 is a block diagram corresponding to the configuration of thesecond embodiment;

FIG. 18 is a diagram schematically illustrating an automatic colorprinter in accordance with the second embodiment;

FIG. 19 is a chart showing on color coordinates average densitiesobtained by photometrically measuring a film image in which a standardobject was photographed on four types of negative film, A, B, C, and D,by consecutively changing the exposure amount;

FIG. 20 is a chart showing on color coordinates image densities in whichmask densities are subtracted from the average densities shown in FIG.19;

FIG. 21 is a chart in which a multiplicity of average densities aredivided into four density levels with respect to the four types ofnegative film and are shown on color coordinates;

FIG. 22 is a chart showing on color coordinates densities in which themask densities are subtracted from the average values;

FIGS. 23 and 24 are charts in which values obtained by subtractingphotometric data for a low-density portion is subtracted from averagevalues are shown on similar color coordinates to those of FIGS. 20 and22;

FIG. 25 is a flowchart illustrating the details of a first step 94;

FIG. 26 is a diagram illustrating a state in which photometry isconducted using a second sensor by planarly dividing a film into aplurality of segments;

FIG. 27 is a diagram illustrating a state in which a mask density isphotometrically measured by the second sensor;

FIG. 28 is a chart illustrating normalization curves;

FIG. 29 is a chart illustrating color coordinates for classifyingtricolor normalized data;

FIG. 30 is a chart illustrating other color coordinates for classifyingtricolor normalized data;

FIG. 31 is a diagram schematically illustrating another embodiment of acolor automatic printer to which the present invention is applicable;

FIGS. 32A and 32B are charts illustrating Formula (17);

FIGS. 33A and 33B are plan views illustrating how calibration isconducted at the time of diagonal photometry; and

FIG. 34 is a chart illustrating relative sensitivity distributions of R,B and G.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the accompanying drawings, a detailed description willbe made of a first embodiment of the present invention. In thisembodiment, the present invention is applied to a color photographicprinter. As shown in FIG. 1, a mirror box 18 and a lamp house 10 havinga halogen lamp are arranged below a negative film 20 which has beenconveyed to a printing section by being loaded on a negative carrier. Alight-adjusting filter 60 is interposed between the mirror box 18 andthe lamp house 10. The light adjusting filter 60 comprises threefilters, a yellow (Y) filter, a magenta (M) filter, and a cyan (C)filter in a conventional manner.

A lens 22, a black shutter 24, and a color paper 26 are arranged inorder above the negative film 20. The arrangement is such that a beam oflight which is applied from the lamp house 10 and is transmitted throughthe light-adjusting filter 60, the mirror box 18, and the negative film20 forms an image on the color paper 26 by means of the lens 22.

A first sensor 28 and a second sensor 30 are disposed in a directioninclined with respect to the optical axis of the above-describedimage-forming optical system and at a position where the image densityof the negative film 20 can be photometrically measured.

The first sensor 28 is connected to an exposure amount calculatingcircuit 42 via a synthetic value calculating circuit 40, while thesecond sensor 30 is directly connected to the exposure amountcalculating circuit 42. Connected to a storage circuit 38 in which theabove-described peculiar value and the spectral sensitivity of thecopying sensitive material are stored. An exposure amount controllingcircuit 44 calculates exposure control amount on the basis of an outputof the exposure amount calculating circuit 42 so as to control thelight-adjusting filter 60.

The first sensor 28 has on a light beam-incident side thereof a filter50 for B light, a filter 52 for G light, and a filter 54 for R light,respectively shown in FIGS. 2A, 2B and 2C, for separating the light inrespective maximum sensitivity wavelength bands of the color paper intoa plurality of separated components. The filter 50 for B light isadapted to separate the light in a wavelength band of 450-485 nmcorresponding to the B light maximum sensitivity wavelength band of thecolor paper into three separated components. The filter 50 has thefollowing interference filters: an interference film B1 for separatingthe light into a component whose central wavelength in the spectraltransmittance distribution is 460 ±5 nm, an interference film B2 forseparating the light into a component whose central wavelength in thespectral transmittance distribution is 470±5 nm, and an interferencefilm B₃ for separating the light into a component whose centralwavelength in the spectral transmittance distribution is 480±5 nm. Theseinterference films B₁, B₂, B₃ are deposited on a glass substrate in sucha manner as to be disposed adjacent to each other. Photoelectricconversion devices 56 are respectively disposed on the lightbeam-transmitting sides of the interference films B₁, B.sub. 2, B₃. Itshould be noted that, in terms of the spectral transmittancedistribution of the filter 50 for B light, the interference films mayhave the same half-width, as shown in FIG. 3A, or may not have the samehalf-width, and the spectral transmittance distributions of the adjacentseparated components may overlap in predetermined wavelength bands, asshown in FIG. 3B.

The filter 52 for G light is adapted to separate the light mainly in awavelength band of 540-560 nm corresponding to the G light maximumsensitivity wavelength band of the color paper into two separatedcomponents. The filter 52 has an interference film G₃ for separating thelight into a component whose central wavelength in the spectraltransmittance distribution is 545±5 nm as well as an interference filmG₄ for separating the light into a component whose central wavelength inthe spectral transmittance distribution is 555±5 nm, the interferencefilms G₃ and G₄ being deposited on a glass substrate in such a manner asto be disposed adjacent to each other. In addition, an interference filmG₂ for separating the light into a component whose central wavelength inthe spectral transmittance distribution is 535±5 nm is disposed adjacentto the interference film G₃, while an interference film G1 forseparating the light into a component whose central wavelength in thespectral transmittance distribution is 510±5 nm is disposed adjacent tothe interference film G₂. The photoelectric conversion devices 56 arerespectively disposed on the light beam-transmitting sides of theinterference films G₁, G₂, G₃, G₄. It should be noted that thehalf-widths of the interference films G₁, G₂ may be greater than thoseof the interference films G₃, G₄, as shown in the spectral transmittancedistribution of the filter 52 for G light shown in FIG. 3B. In addition,in this filter as well, the spectral transmittance distributions of theseparated components may overlap in predetermined wavelength bands.

The filter 54 for R light is adapted to separate the light mainly in awavelength band of 680-710 nm corresponding to the R light maximumsensitivity wavelength band of the color paper into three separatedcomponents. The filter 54 has the following interference films: aninterference film R₃ for separating the light into a component whosecentral wavelength in the spectral transmittance distribution is 690±5nm, an interference film R₄ for separating the light into a componentwhose central wavelength in the spectral transmittance distribution is700±5 nm, and an interference film R₅ for separating the light into acomponent whose central wavelength in the spectral transmittancedistribution is 710 ±5 nm. These interference films G₃ and G₄ aredeposited on a glass substrate in such a manner as to be disposedadjacent to each other. In addition, an interference film R₁ forseparating the light into a component whose central wavelength in thespectral transmittance distribution is 630 ±5 nm and an interferencefilm R₂ for separating the light into a component whose centralwavelength in the spectral transmittance distribution is 660+5 nm aredisposed adjacent to the interference film R₃. The photoelectricconversion devices 56 are respectively disposed on the lightbeam-transmitting sides of the interference films R₁, R₂ , R₃, R₄, R₅ inthe same way as the filter 50 for B light and the filter 52 for G light.It should be noted that the half-widths of the interference films R₁, R₂may be greater than those of the interference films R₃, R₄, R₅, as shownin the spectral transmittance distribution of the filter 54 for R lightshown in FIG. 3C.

The filter 50 for B light may be fabricated in the following manner: Theinterference film B1 is first deposited in a state in which the portionsto be deposited with the interference films B2, B3 are masked. Theinterference film B2 is then deposited in a state in which the portiondeposited with the interference film B1 and the portion to be depositedwith the interference film B3 are masked. The interference film B3 isfinally deposited in a state in which the portions deposited with theinterference films B1, B2 are masked. Incidentally, both the filter 52for G light and the filter 54 for R light may be fabricated in the sameprocedure as that for the filter 50 for B light.

In addition, as shown in FIG. 4, the first sensor 28 is arranged suchthat the filter 50 for B light, the filter 52 for G light, and thefilter 54 for R light are arranged on a rotatable disk 58 along theperipheral direction thereof. Alternatively, the first sensor 28 may bearranged such that each of the filters 50, 52, 54 is divided into aplurality of filter pieces with one interference film as a unit, andthese filter pieces are arranged along the peripheral direction of thedisk 58, as shown in FIG. 5.

Although in the foregoing examples the filter is arranged in such amanner that each of the interference films corresponds to one separatedcomponent, the filter may be alternatively arranged such that aplurality of interference films correspond to one separated component.FIGS. 6A to 6C show examples of the filter for G light thus arranged.FIG. 6A illustrates an example in which the interference films G1 to G4are arranged in a striped configuration; FIG. 6B shows an example inwhich the interference films G1 to G4 are arranged in a mosaicconfiguration; and FIG. 6C shows an example in which the interferencefilms G1 to G4 are arranged in a radial configuration. A two-dimensionalimage sensor such as a CCD, which has a multiplicity of photoelectricconversion elements, is provided on the light beam-emergent sides ofthese filters. Such filters are capable of photometrically measuring theoriginal picture of the film uniformly since a plurality of interferencefilms correspond to one separated component. It should be noted that, inthis case, it is necessary to effect calibration by such as setting asensor output corresponding to the base density of the negative film toa reference value 0.0 prior to photometry.

Furthermore, in the foregoing embodiment, in cases where there is awavelength band in which adjacent ones of separated components overlapeach other, the filters allowing the adjacent separated components to betransmitted therethrough are preferably not disposed at adjacentpositions so as to prevent the leakage of the respective components. Forinstance, by arranging the interference film G3 and the interferencefilm G4 in such a manner as not to be adjacent to each other as in thecase of the filter for G light shown in FIG. 2D, the light which hasbeen transmitted through the interference film G3 can be prevented frommixing in the light light which has been transmitted through theinterference film G4.

The second sensor 30 comprises a tricolor separation filter and atwo-dimensional image sensor, and is adapted to photometrically measurethe R, G, and B light by dividing the image of the negative film 20 intoa multiplicity of fragments. Here, the light in the range of 600-750 nmcan be adopted as the R light; the light in the range of 500-600 nm, asthe G light; and the light in the range of 400-500 nm, as the B light.The aforementioned maximum sensitivity wavelength bands are included inthese ranges.

In the case of the sensor having the filters shown in FIGS. 2A to 2C,the following are stored in the storage circuit 38: peculiar values S₁₁,S₂₁, S₃₁, ... obtained by integrating spectral sensitivity distributionsS.sub.λ1, S.sub.λ2, ... of the respective photoelectric conversionelements with respect to λ with integral sections set as being identicalto small sections, as well as spectral sensitivities P₁, P₂, P₃, ... ofthe copying sensitive material. It should be noted that, instead of theaforementioned peculiar values, the spectral sensitivity distributionsof the respective regions of the sensors may be stored and, instead ofthe aforementioned spectral sensitivities of the copying sensitivematerial, the spectral sensitivity distributions per se may be stored.

FIG. 8 illustrates a routine of calculation by the synthetic valuecalculating circuit 40 and the exposure amount calculating circuit 42.In Step 100, photometric values Fi corresponding to the respectivephotoelectric conversion elements and photometrically measured by thefirst sensor 28 are fetched. In Step 102, peculiar values Sij stored inthe storage circuit 38 are read. In an ensuing Step 104, true values Tiare estimated by using the photometric values F1 and the peculiar valuesSij, as described above. In an ensuing Step 106, the spectralsensitivities Pi of the copying sensitive material are read from thestorage circuit 38, and, in Step 108, the synthetic values Tp arecalculated on the basis of the aforementioned Formula (6). In Step 110,a basic exposure amount Dp is calculated in accordance with thefollowing formula by assuming the synthetic values Tp as Tr, Tg, Tb, andaverage photometric values of the picture of the second sensor as mr,mg, mb: ##EQU12## where r, g, and b represents red, green, and bluecolor, respectively, and p is one of r, g, and b.

Formula (7) effects color control by the first sensor and densitycontrol by the second sensor. Specifically, the difference in color ofthe first sensor is added to the tricolor average density of the secondsensor. The correction value of the basic exposure amount for correctionby the second sensor may be obtained by determining a correction valueof density with respect to the tricolor average density of the secondsensor and color correction values with respect to mr, mg, mb of thesecond sensor and by adding the same to the basic exposure amount Dp. Itgoes without saying that, in order to increase the accuracy ofcalculation of these values, the spectral sensitivity distribution ofthe second sensor is closer to that of the copying sensitive material.

It should be noted that the basic exposure amount Dp may be calculatedin accordance with the following Formulae (8), (9), and (10). ##EQU13##

The exposure amount controlling circuit 44 controls exposure amount bycontrolling the light-adjusting filter in accordance with the basicexposure amount Dp.

Specifically, in order to correct the density based on the photographedscene, color failures and the like, the correction amount is calculatedon the basis of the photometric value of the second sensor, and exposureamount is controlled by setting as an exposure control value a value inwhich that correction value is added to the basic exposure amount. Themethod of calculating the correction amount and the method ofcontrolling exposure amount are disclosed in detail in Japanese PatentLaid-Open Nos. 311241/1988 and 311242/1988.

As described above, in accordance with this embodiment, it is possibleto obtain an advantage in that, as disclosed in Japanese PatentLaid-Open No. 311241/1988, the types of film having different filmcharacteristics can be printed under the same printing conditions, andprints of higher quality than conventional prints can be produced fromvarious types of film. In addition, if this embodiment is applied to acolor copying machine, original pictures having different spectralsensitivity distributions (photographic original pictures, printingoriginal pictures, illustrations, solid bodies, etc.) can be copiedunder the same copying conditions.

Although in the above-described embodiment the basic exposure amount Dpis expressed such as in Formulae (7) to (10), a value in which acharacteristic amount of the image (e.g., a maximum density, a minimumdensity, a partial area density, or the like) determined from thephotometric values of the second sensor is added may be set as the basicexposure amount. In addition, exposure control may be carried out suchthat by preparing a correction formula (or conversion table) of thephotometric values of the second sensor on the basis of therelationships of correspondence between the photometric values of thefirst and second sensors, the photometric values of the second sensorare converted to values approximate to those of the first sensor, andexposure amount is determined on the basis of the converted values.Alternatively, the exposure amount determined by the second sensor maybe corrected by the photometric values determined by the first sensor.In this case, the difference between the basis exposure amountsdetermined from the first and second photometric values may be set as acorrection value.

In addition, although a description has been given of an example inwhich peculiar values are stored in the storage circuit, an arrangementmay be alternatively provided such that the spectral sensitivitydistributions of the respective regions of the sensors are stored inadvance, and peculiar values are determined through calculation.

Furthermore, although in the above a description has been given of anexample in which the spectral sensitivity distribution of an originalpicture is estimated on the basis of the photometric values and of theweight determined from the spectral sensitivity distributions of thesensors, it is possible to estimate the weight. In other words, as shownin FIGS. 9A and 9B, if it is assumed that the spectral sensitivitydistributions of the respective regions of the sensors are S.sub.λ1,S.sub.λ2, S.sub.λ3, that weights to be added to these spectralsensitivity distributions are W₁, W₂, W₃, the spectral sensitivities tobe determined, i.e., the spectral sensitivities of the copying sensitivematerial, are M₁, M₂, M₃, and if they are expressed as a matrix, theycan be expressed as M=W·S. Hence, the weight can be expressed asfollows:

    W=S.sup.-1 ·M                                     (11)

Accordingly, if the spectral sensitivity distributions of the respectiveregions of the sensors and the spectral sensitivity distribution of thecopying sensitive material are stored in advance in the storage circuit,and the calculation of Formula (11) above is carried out, it is possibleto determine from the photometric values of the sensors the weight W forestimating a photometric value equivalent to a value measured by asensor having a spectral sensitivity distribution identical with orsimilar to the spectral sensitivity distribution of the copyingsensitive material. Then, if the photometric values of the first sensor28 are multiplied by the aforementioned weight and are integrated withrespect to the wavelength, it is possible to obtain the synthetic valueTp.

Furthermore, although in the above a description has been given of aprinter in which a photometric portion and a light-receiving portion arelocated in the same position, it is possible to employ a printer inwhich the photometric portion and the exposure portion are separatedfrom each other. The second sensor may be a line sensor. Furthermore, anapplicable printer is not restricted to the one shown in FIG. 1, and thepresent invention is readily applicable to a printer of the type inwhich scanning is effected by driving the film.

Next, a description will be given of examples of the first sensor whichcan be used in the present invention. A first example of the firstsensor 28 comprises a two dimensional image sensor 32 and a metalinterference filter 34, as shown in FIG. 10. The two-dimensional imagesensor 32 is so constructed as to have a pixel density in which a unitwavelength is set as one pixel. As the unit wavelength, a value in therange of 2-40 nm, e.g., 5-30 nm, is preferable. The interference filmsare preferably arranged such that they each of them is formed into awedge shaped configuration so that its thickness changes continuously.The metal interference filter 34 is arranged such that a thin film 12 ofmagnesium fluoride MgF₂ whose thickness is changed into the wedge-shapedconfiguration is formed on a thin film 16 of silver Ag deposited on atransparent substrate 11, and a thin film 14 of silver Ag is furtherdeposited thereon. Thicknesses of the thin films 14, 16 may be fixed.Also, since the transmittance can be controlled by the thicknesses ofthe Ag thin films 14, 16, the thin film 12 may be formed in such amanner that its thickness becomes gradually larger from its thickportion to its thin portion. This arrangement is adopted so as to lowerthe sensitivity of the sensor with respect to a long wavelength band(e.g., 500 nm 750 nm) of the spectral light relative to its sensitivityto a short wavelength band (e.g., 420 nm-500 nm) thereof, since thequality of light of the halogen lamp is small in the short wave band of420 nm-500 nm and the sensitivity of the two-dimensional image sensor islow in the short wave band. In order to lower the sensitivity of thesensor, in the example shown in FIG. 10, the thicknesses of the thinfilms 14, 16 on the long wave band-side thereof are made large, therebylowering the transmittance. The central wavelength of light separated bythis metal interference filter 34 is determined in correspondence withthe thickness of the wedge-shaped thin film 12, the greater thethickness, the more the central wavelength is located on the short-waveside.

It is necessary to jointly use a sharp cut filter or band-pass filter 13so as to cut unnecessary interfering light, such as by using secondaryinterfering light for the short wavelength band and primary interferinglight for the long wavelength band. Furthermore, a protective layer ofAg film (SiO film, MgF₂ film) may be superposed on the thin film so asto prevent the deterioration of the film.

FIG. 11 illustrates a second example of the first sensor, in which themetal interference filter comprises the thin film 12 of magnesiumfluoride MgF₂ with its width changing in the form of a wedge, as well asthe thin films 14, 16 of silver Ag which are deposited with the thinfilm 12 placed therebetween and have uniform thicknesses. Additionally,in order to cut unnecessary interfering light, the sharp cut filter orband-pass filter 13 is superposed thereon. In this first sensor, inorder to lower the sensor sensitivity to the long wave band relative tothe its sensitivity to the short wave band, the area of pixels on theshort-wave side of the two-dimensional image sensor is made larger thanthe area of pixels on the long wave side thereof. Since the quantity oflight received by one pixel becomes large thanks to the increased area,the sensitivity on the short-wave side becomes higher than thesensitivity on the long-wave side.

It should be noted that although in the above example the interferencefilm is formed into the wedge-shaped configuration so as to change itsthickness, the thickness of the interference film may be changed intothe configuration of steps, as shown in FIG. 12. In FIG. 12, the samecomponents as those of the above example are denoted by the samereference numerals, and a description thereof will be omitted. In thisstepped interference filter, the photometric conversion elements 56 aredisposed in correspondence with its portions having the same thickness,but the two-dimensional image sensor 32 may be disposed in the same wayas described above. If the thicknesses of this stepped interferencefilter are set to be those allowing the central wavelengths of 510, 535,and 555 nm to be obtained, respectively, this filter can be made similarto the filter for G light described above. Also, the filters for B and Rlight can be fabricated in a similar manner. In addition, as shown inFIG. 13, a transmitted light quantity controlling filter 36 such as acolor filter, an ND filter, or the like may be provided on the longwavelength-band side of the metal interference filter 34 so as to lowerthe sensitivity. Furthermore, instead of magnesium fluoride, cryolitemay be used as the film having a low refraction index.

FIG. 14 illustrates still another example of the interference filter.This interference filter is arranged such that alternating films,consisting of a film 52 formed of a high refractive index material, suchas titanium oxide TiO₂, cerium oxide CeO₂, or the like, and a film 54formed of a low refractive index material, such as magnesium fluorideMgF₂, are vacuum deposited on a glass substrate 50. Since therelationship between the central wavelength λ, the refractive index n,and the film thickness d can be expressed by λ=4·n·d, the filmthicknesses are determined on the basis of this formula. As the ratiobetween the thickness of the film 52 and that of the film 54, 1:3 or 3:1is ordinarily used. In order to make the film thickness to changecontinuously, it suffices to dispose the substrate such as as to beinclined with respect to a vapor generating source and effect depositionusing a vacuum deposition machine, or it suffices to effect depositionby disposing a mask for controlling the film thickness in front of thesubstrate. Instead of the substrate, deposition may be effected on theimage sensor.

If an inert gas such as nitrogen gas is sealed in and sealed with coverglass after formation of the filter or deposition of the filter on theimage sensor, it is possible to improve the durability of the depositedfilm. In order to cut unnecessary transmitted light on the short-waveside or the long-wave side, a colored glass filter for cuttingultraviolet rays or infrared rays or a dielectric multilayered filter isjointly used with this filter.

FIG. 15 illustrates still another example the first sensor. This firstsensor comprises the two-dimensional image sensor 32, an interferencefilter 34A for the short wave band provided on the transparent substrate11, and an interference filter 34B for the long wave band. The maximumthickness of the interference filter 34A for the short wave band isformed to be greater than the maximum thickness of the interferencefilter 34B for the long wave band. In addition, the area of the pixelson the short wave band side of the two-dimensional image sensor 32 iswider than the area of the pixels on the long-wave side thereof, therebylowering the sensitivity to the long wave-band side of the spectrumrelative to the sensitivity to the short wave-band side thereof.

The first sensor may comprise three wedge-shaped or stepped interferencesensors, including the filter for R light (for 680-710 nm), the filterfor G light (for 540-560 nm), and the filter for B light (for 450-485nm) for photometrically measuring a photometric region by dividing itinto three wavelength bands corresponding to the maximum sensitivitywavelength bands of the color paper, and may also comprise atwo-dimensional image sensor. Naturally, the sensor may have the threeinterference filters integrated into one unit, or may have threeseparate interference filters, or may have only two of them integratedinto a unit. In cases where the sensor is arranged with three separatefilters, the interfering light can be selected readily and the quantityof transmitted light can be easily controlled by using a band-passfilter or a sharp cut filter. The wavelength region of each interferingfilter may be narrowed more than the aforementioned range so as toenhance the accuracy in the spectral wavelength and make the filtercompact.

A description will now be given of a second embodiment of the presentinvention.

In the description of this embodiment, the components, members, andportions that are similar to those of the first embodiment will bedenoted by the same reference numerals employed in the first embodiment,and a description thereof will be omitted.

The first sensor 28 and a second sensor 130 are disposed in a directioninclined with respect to the optical axis of the image-forming opticalsystem and at a position where the image density of the negative film 20can be photometrically measured. The first sensor 28 is arranged asshown in FIGS. 10 to 15 in accordance with the first embodiment, whilethe second sensor 130 is constituted by a two-dimensional image sensor,a line sensor, or the like, and effects photometry along a scanning lineSL by planarly dividing the negative image into a multiplicity of pixelsSn, as shown in FIG. 20. In this case, the photometry of each pixel isconducted with respect to the three primary colors of B, G and R.

The first sensor 28 and the second sensor 130 are connected to anexposure control circuit 140 for controlling exposure amount bycalculating an exposure amount control value and controlling the lightadjusting filter 60. This exposure control circuit 140 is constituted bya microcomputer having a read only memory (ROM) in which the program ofan exposure control routine shown in FIG. 16 and other data are stored,a random access memory (RAM), a central processing unit (CPU).

A description will now be given of the exposure amount control routinewith reference to FIG. 16. In Step 186, the photometric values SP.sub.λof the first sensor 28 are fetched and, in Step 188, first average imagedensities PD1j of the respective R, G, and B components are calculatedin accordance with the aforementioned Formula (12). In an ensuing Step190, photometric values ti of the second sensor 130 are fetched. In Step192, second average image densities PD2j of the respective R, G, and Bcomponents are calculated in accordance with the aforementioned Formula(13). In Step 194, third average image densities PD3j are calculated, aswill be described later. Then, in Step 196 an exposure control value Ejis calculated by using the aforementioned Formulae (14) and (15). InStep 198, the exposure amount is controlled on the basis of thisexposure control value Ej. Formula (14) allows a basic exposure amountto be determined on the basis of the first average image densities PDljand an exposure amount correction value to be determined on the basis ofF·f (PD3j, PD2j). In Step 186, the photometric values SP.sub.λ of thefirst sensor may not be the photometric values themselves, and maynaturally be true photometric values or corrected photometric values inwhich the spectral distributions of the spectral components or separatedcomponents are incorporated into the quantity of light.

A detailed description will now be given of the contents of Step 194.

First, a description will be given of the basic principle ofcalculation. FIG. 19 is an example in which a standard object wasphotographed by using four types of negative films A, B, C, and D and byconsecutively changing the exposure amount, and in which averagedensities obtained by photometrically measuring the film images areshown on color coordinates with R G set as the abscissa and G B as theordinate. FIG. 20 shows on color coordinates image densities in whichthe mask densities of the films are subtracted from the averagedensities shown in FIG. 19. As can be appreciated from FIG. 20, thedensities of image portions of the respective films in which the maskdensities are subtracted from the average densities are substantiallyapproximate to each other with the exception of a high. density portionof the film C. FIG. 21 shows on color coordinates average densities of amultiplicity of images (about 100 frames) with respect to theaforementioned four types of negative films, the average densities beingdivided into four density levels. An upper end of each broken lineindicates each mask density. Three of the four types of film aresubstantially different. FIG. 22 shows on color coordinates densities inwhich the mask densities are subtracted from the respective averagedensities as well as average values of the densities of the four films.In this chart, the densities of film image portions are substantiallyapproximate to each other in the same manner as FIG. 20.

However, such a coincidence has not been found with negative filmsproduced up until recent years. Combinations of negative films andpapers manufactured by only one or a very few number of manufacturershave been prevalent in most cases. It was sufficient if favorablephotographic prints could be obtained in those combinations. Nosufficient consideration has been given to the other combinations. Inrecent years, however, as a result of the worldwide diffusion of varioustypes of films, the number of possible combinations of various types ofnegative films and various types of color papers has reached an enormousscale. In order to ensure that any combination can be used, it isnecessary that the characteristics of the gradation balance of variousfilm types be approximate to each other. The results of FIGS. 19 and 21show that the gradation balance characteristics of the various types offilms are approximate to each other.

However, the characteristics of coloring materials used in various filmsare naturally different, and the light-sensitive material designingtechniques are not similar, so that the mask densities are not identicalfor the respective film types.

FIGS. 23 and 24 illustrate cases in which values in which, instead ofthe mask densities, photometric data on low-density portions of filmimage portions are subtracted from average densities are shown on thesame color coordinates as those of FIGS. 20 and 22. A better coincidencecan be obtained for important density regions with respect to the fourtypes of films than subtracting the mask densities.

Accordingly, average density values of one film in which lowdensity-portion photometric data including the mask density aresubtracted from photometric values may be used as the image-portioncharacteristic of each type of film. In addition, an average value of aplurality of average density values mentioned above may be used for eachtype of film.

As described above, irrespective of the type of film, a similarity canbe noted for the tricolor photometric data in which the mask density ora low density close to it, i.e., either lowest-density data, other thanan image recorded portion, of a color film, or lowest-density data onthe image recorded portion of the color film is subtracted from theaverage density. For this reason, in this embodiment, tricolor correctedphotometric data is obtained by correcting tricolor photometric datawith low-density-portion photometric data by such as subtractingphotometric data on a low-density portion of the color film, includingthe image recorded portion, from the tricolor photometric data obtainedby dividing the color film with an image recorded thereon into amultiplicity of segments and by photometrically measuring the segments.This tricolor corrected photometric data is transformed into tricolornormalized data by being normalized in accordance with a predeterminedcondition of transformation. This tricolor normalized data is classifiedby being compared with a reference value, the tricolor photometric datais selected in correspondence with this classification, and exposureamount is determined on the basis of an average value of the tricolorphotometric data selected.

As has been described with respect to the mask density, since the maskdensities do not coincide with each other among the types of film, it ispreferable to determine the low-density-portion photometric data,including the mask density, with respect to each type of color film.

A description will now be given of a routine for calculating the averagedensity in accordance with the above-described basic principle. In Step190, tricolor photometric data photometrically obtained by the secondsensor 130 is fetched, and a determination is made in Step 201 as towhether or not photometry is to be effected for an initial stage ofprinting, i.e., whether or not photometry is to be effected for aprinting-start image frame or for a number of frames beginning with theprinting-start image frame (a maximum of six frames or thereabouts). Ifthe case is photometry for the initial stage of printing, the operationproceeds to Step 202, and if it is not photometry for the initial stageof printing, the operation proceeds to Step 204. In Step 202, by usingvalues stored in advance in the ROM, e.g., an average mask density,tricolor low. density-portion photometric data MIN (R), MIN (G), and MIN(B) are calculated and are stored in the ROM. Parenthetically, theaverage mask density is determined by averaging the mask densities oraverage lowest densities of various types of film. A comparison is madebetween a value which is greater by a predetermined value α (e.g.,0-0.6) than the average mask density on the one hand, and thelowest-density value of the tricolor photometric data or an averagevalue of the tricolor photometric data on the other. When (the averagemask density+α)>(a lowest-density value of the tricolor photometric dataor an average value of the tricolor photometric data), thelowest-density value of the tricolor photometric data or an averagevalue of the tricolor photometric data is set as the low-density-portionphotometric data. Meanwhile, when (the average mask density +α)<(alowest-density value of the tricolor photometric data or an averagevalue of the tricolor photometric data), the value which is greater bythe predetermined value α than the average mask density is set as thelow-density-portion photometric data.

It should be noted that a lowest-density value of the tricolorphotometric data obtained with a photometric area 30A of the secondsensor 130 straddling image frames 120A, 20B, as shown in FIG. 27, maybe set as the low-density-portion photometric data. In addition, thelow-density-portion photometric data may be determined for each filmtype by storing in advance the mask density, i.e., the low.density-portion photometric data, in the ROM for each type of film andby detecting a so-called DX code indicating the film type to determinethe film type.

Since the low-density-portion photometric data is determined asdescribed above, there are cases where this low-density-portionphotometric data is the lowest-density data on an image-recorded portionof the color film and where it is the lowest-density data on a portionother than the image recorded portion of the color film (i.e., the maskdensity). This lowest-density-portion photometric data is determined byconducting photometry of a printing start image frame or for a number offrames beginning with the printing-start image frame (a maximum of sixframes or thereabouts).

In the ensuing Step 204, tricolor corrected photometric data R, G, B arecalculated by subtracting the low-density-portion photometric data MIN(R), MIN (G), MIN (B) from the respective tricolor photometric data.This corrected photometric data show characteristics that closelyresemble each other irrespective of the type of film, as describedabove.

In an ensuing Step 206, the tricolor normalized photometric data iscalculated by normalizing the corrected photometric data R, B bytransforming the same into the density of G by using normalizationcurves shown in FIG. 28. The film density and the gradation balance varydepending on the exposure level and the type of film, so that when anidentical object is photographed, the image density and color vary dueto the exposure level and the type of film. The normalization processingis provided to obtain a fixed density and color on the negative film bycorrecting the same with respect to the identical object irrespective ofthe exposure level and the type of film. In addition, the normalizationtable is prepared on the basis of a curve indicating the relationshipbetween an average value of the photometric data G and an average valueof the photometric data R, as well as a curve (FIG. 28) indicating therelationship between an average value of the photometric data G and anaverage value of the photometric data B, these data being stored in theRAM.

The aforementioned corrected photometric data R, B are transformed intothe density of G by using the above described normalization table. Asshown in FIG. 28, for instance, an average value R₃ of the correctedphotometric data R₂ and R₃ is transformed into an average value G₃ of G₂and G₃, and an average value B₃ (not described) of corrected photometricdata of B₂ -B₃ is similarly transformed into an average value G₃. Atthis time, the corrected photometric data G is used as it is withoutbeing transformed. As a method of this normalization, it is possible touse the methods disclosed in Japanese Patent Laid-Open Nos. 1039/1981and 144158/1987 in addition to the above described method.

Through such normalization of corrected photometric data, it is possibleto use the same color coordinates even if the film density and the filmtype differ, and it is possible to set the origin of the coordinate atan arbitrary color. If it is assumed that an average value of thephotometric data on a multiplicity of films becomes gray, the threecolors of the normalized data on a gray object come to assume anidentical density by means of the above described normalization. Inpractice, since the average value of the photometric data on amultiplicity of films is slightly different from gray, a correction ismade by an amount corresponding to that difference.

In an ensuing Step 208, as shown in FIG. 29, the tricolor normalizeddata is classified by determining to which color region the tricolornormalized data belongs, between a color region A_(a) including theorigin and a color region A_(b) excluding the color region A_(a). bothregions being set on color coordinates with a difference, R-G, betweenthe normalized data R and G taken as the abscissa and a difference, G-B,between the normalized data G and B taken as the ordinate. The tricolornormalized data is classified with a boundary between the color regionA_(a) and the color region A_(b) serving as a point of demarcation, sothat the tricolor normalized data is classified into data belonging to aregion where the color difference from a reference value (origin) issmall and into data belonging to a region where the color differencefrom the reference value is large.

The following table shows examples of a combination of the colorregions, the tricolor normalized data classified for each of these colorregions, and the tricolor photometric data corresponding to the tricolornormalized data.

                  TABLE                                                           ______________________________________                                                     Tricolor Photo-                                                                             Tricolor Normal-                                   Photometric  metric Data   ized Data                                          Region                                                                              No.        R      G     B    R     G    B                               ______________________________________                                        Aa    1          0.72   1.03  1.17 0.60  0.63 0.57                            Aa    2          0.69   1.05  1.19 0.57  0.65 0.59                            Ab    3          0.62   1.15  1.21 0.50  0.75 0.61                            Ab    4          0.60   1.18  1.20 0.48  0.78 0.60                            --    --                --               --                                   --    --                --               --                                   --    --                --               --                                   ______________________________________                                    

It should be noted that although in the above the tricolor normalizeddata is classified by using color coordinates using G B and R G as axes,it is possible to use as two- or three-dimensional color coordinates acoordinate axis having as its axis one color or a combination of two ormore colors of the three primaries (e.g., Dx Dy, Dx/Dy, Dx/(Dx+Dy+Dz),aDx+bDy+cDz, Dx/K, etc., where x, y, and z respectively represent amutually different one color selected from among R, G, and B, and a, b,c, and K are constants), i.e., a coordinate axis having as its axis acolor difference other than the above or a color ratio. In addition, aplurality of color regions may be determined in correspondence with adistance from a reference value. As this reference value, it is possibleto adopt such as an origin of the color coordinates used, a valueconcerning a specific color of the original image, a value obtained froman average value of a multiplicity of images, a minimum value ofphotometric data, a value obtained from photometric data on a specificimage, a predetermined specific constant, and so forth. Furthermore, thereference value may be a value given by a functional expression or atable. In this case, the functional expression or table may be such thata reference value changes depending on, for instance, an image density.It should be notes that as a specific color of the original image, aneutral color, a color of skin, or a color determined from an averagevalue of a multiplicity of images.

In addition, as a color region, it is possible to use a color region inwhich a distance to its periphery from an origin provided on coordinateshaving a neutral color as an origin is irregular, as shown in FIG. 30.

In Step 210, the tricolor photometric data corresponding to the tricolornormalized data belonging to the color region A_(a) in which a colordifference from the reference value is small is selected and stored inthe RAM. In Step 212, the selected tricolor photometric data isarithmetically averaged, and the third average image density PD3j iscalculated. It should be noted that in cases where the tricolornormalized data is classified on the basis of coordinates having colorratios as axes, the tricolor photometric data corresponding to thetricolor normalized data belonging to a color region whose color ratiofrom a reference value is small is selected, and this tricolorphotometric data is averaged so as to calculate the third average imagedensities PD3j. In these cases, a setting is provided as F=1.0.

As can be appreciated from FIGS. 20, 22, 23, 24, the color balancebetween R and G is substantially fixed in terms of the density, and thedensity of B becomes relatively higher than the density of G as thedensities of G and B increase. Accordingly, in this case, it isnecessary to ascertain to what extent a difference exists between thephotometric data and the low-density-portion photometric data such asthe mask density. An error of ±0.3 can be allowed for the density (e.g.,density of G) if the color balance is allow to vary by ±0.05 (since theimage density of a gray object varies due to different photographinglight sources, cameras, chronological changes of the film,characteristics between lots, etc., the normalization curve also has amargin of variation, so that this allowable error is set at ±0.05).Namely, if the error of the image density of the photometric data iswithin ±0.3, the color balance can be estimated with an error of within±0.05. As a result, it suffices if the low-density-portion photometricdata is within ±0.3 with respect to the mask density or the mask densityplus α.

It should be noted that this embodiment is also applicable to the methodin which image densities determined from photometric values are storedin the storage means for each type of film, the photometric values arethen normalized by using the multiplicity of image densities stored, andcorrection amount is determined by using the normalized data. In thiscase, since the resultant correction amount is determined from thetricolor normalized data, it is necessary to revert the correctionamount to the level of a photometric value by performing an inversecalculation to that of normalization. This inverse calculation can beattained by setting F as a coefficient or a functional expression.

In addition, color control may be effected by using the first averageimage densities PDlj, and density control may be effected by using thesecond average image densities. In this case, the following averagevalue of density is used as the second average image density: ##EQU14##where KD is a constant which is determined by calibration.

As described above, in this embodiment, the first average imagedensities determined from photometric values of the first sensor arecompared with the second average image densities determined fromphotometric values of the second sensor, the basic exposure amount isdetermined on the basis of the first average image densities withoutcorrecting the exposure amount with respect to spectral differences ofthe sensors, and correction is effected by using the second and thirdaverage image densities. By directly employing the first average imagedensities, higher color correction performance can be obtained withoutdeteriorating the correction performance for the film types, sincecorrection with respect to an object through the second and thirdaverage image densities is of such quality that the spectral photometricaccuracy may not be high.

It should be noted that although in the above a description has beengiven of an example in which the first and second sensors are disposedin the exposure system, an arrangement may be alternatively providedsuch that the photometric system is disposed upstream of the exposuresystem, and the first and second sensors are disposed in thisphotometric system. In addition, either the first or second sensor maybe disposed in the exposure system, the remaining sensor being disposedin the photometric system. Additionally, an arrangement may be adoptedsuch that the photometric values of the sensors are transmitted to theexposure control circuit on an on-line basis. This example includes acombination of a color film analyzer having the second sensor and aprinter having the first sensor.

A description will now be given of a third embodiment of the presentinvention.

In the description of this embodiment, those members, components, andportions that are similar to those of the first embodiment are denotedby the same reference numerals as those used in the first embodiment,and a description thereof will be omitted.

In this embodiment, the present invention is applied to a colorphotographic printer. As shown in FIG. 31, the first sensor 28 isdirectly connected to an exposure amount calculating circuit 343 via aweighting circuit 340, while the second sensor 30 is connected to theexposure amount calculating circuit 343. An exposure amount controllingcircuit 344 is adapted to calculate exposure control amount on the basisof an output of the exposure amount calculating circuit 342 and controlthe light-adjusting filter 60.

The weighting circuit 340 determines a synthetic value Si on the basisof spectral photometric values by using a weight coefficient Kij asshown in Formula (16) below: ##EQU15##

In Formula (16), Sij/Soij is a transmittance at each wavelength ij ofthe film image, and the synthetic value Si is a density in a case wherethe density is assumed to be 0 when film is absent. Naturally, a valuein which αi, βi are added thereto, S'i=αi+βiSSi, may be used in thecalculation of exposure amount. Soij is a spectral photometric value ata pixel ij when the film image is absent, and Sij is a spectralphotometric value of light transmitted through the original picture atthe same pixel. i represents each wavelength band of R, G, and B, and jrepresents the respective number of photometric wavelengths (=the numberof pixels) among R, G, and B.

If it is assumed that L is a constant (which is determined on the basisof the wavelength interval or wavelength distribution of spectral light,correction due to insertion of a reference filter or a film, or othersimilar factor; the value may be altered for each wavelength), that j isset with respect to wavelengths at 10 nm intervals, that PSij is avirtual spectral sensitivity to the wavelength of a copying materialincluding the exposure optical system, and that Soij is a spectralphotometric value at each pixel j in the case where the film is absent,then the aforementioned weight coefficient Kij is determined fromFormula (17). This coefficient Kij may be stored in advance in theapparatus, or determined for each apparatus.

    PSij=Kij(L/Soij)                                           (17)

FIGS. 32A and 32B illustrate Formula (17). The dotted line in FIG. 32Bshows a relative spectral sensitivity distribution of the copyingmaterial.

It should be noted that the present invention is not to be restricted toFormulae (16) and (17). In particular, it is preferable to take intoaccount the wavelength width of the spectrum, the spectral wavelengthinterval, and a distribution configuration due to the fact that spectraare not ideal. Basically, it suffices if Kij is determined in such amanner that the area indicated by the dotted line (a relative spectralsensitivity distribution of the copying material) and the area indicatedby the solid line (a sensitivity distribution of each pixel of thesensor) agree each other.

FIG. 34 illustrates the relative spectral sensitivity distributions ofR, G, and B resulting from the weighting of the first sensor in caseswhere ideal spectra have been obtained. That is, the drawing shows theweight of each spectrum at a time when the maximum sensitivitywavelengths of B, G, and R at the first sensor are set to 1.0. When themaximum sensitivity is set to 1.0, FIG. 34 is equivalent to the relativesensitivity distribution of B, G, and R. The dotted line shows thespectral sensitivity distributions of the copying sensitive material.

Since the first and second sensors effect photometry diagonally withrespect to the optical axis, calibration is effected in such a mannerthat equal photometric values will be obtained over the entirephotometric picture when the film is absent, or when the reference filmor filter is inserted, FIG. 33A illustrates the manner in which thefirst sensor is arranged such that the thickness of the interferencefilters will change in the vertical direction, and the film picture isphotometrically measured diagonally by the first sensor. FIG. 33B showsthe manner in which positions A-H on the film shown in FIG. 33A areprojected onto the sensor. The light is separated in the verticaldirection, and the film position is projected in the horizontaldirection. The sensitivity and correction values are adjusted in advancethrough calibration so that equal photometric values (e.g., set to 0)will be obtained at positions A-H projected. By adding the photometricvalues at A-H with respect to each spectral component, the dependency onthe image position in the film due to inclined photometry can beeliminated.

In addition, photometry may be effected by reducing in the direction ofA-H by means of a cylindrical lens, and the pixels of the sensor may bemade rectangular, as shown in FIGS. 10 and 11 in accordance with thefirst embodiment.

If output values of the weighting circuit 340, i.e., the syntheticvalues Si, are Sr, Sg, and Sb, and that the picture average photometricvalues of the second sensor are mr, mg, and mb, the exposure amountcalculating circuit 342 calculated a basic exposure amount Di inaccordance with the following formula: ##EQU16## where r, g, and brepresent red, green, and blue color, and i is any one of r, g, and b.

In Formula (18), the color difference of the first sensor is added tothe tricolor average density of the second sensor so as to provide amatching in the average density of the picture between the first sensorand the second sensor. The correction value for the basic exposureamount by means of the second sensor can be obtained if a densitycorrection value is determined with respect to the tricolor averagedensity of the second sensor and color correction values are determinedwith respect to mr, mg, and mb of the second sensor, and if they areadded to the basic exposure amount Di.

It should be noted that the basic exposure amount Di may be calculatedin accordance with the following Formulae (19), (20), and (21):

    Di=(mr+mg+mb)/3+(Si-Sg)                                    (19)

    Di=mg+(Si-Sg)                                              (20)

    Di=Si                                                      (21)

In addition, the exposure amount controlling circuit 344 controlsexposure amount by controlling the light-adjusting filter in accordancewith the basic exposure amount Di.

In order to correct the density, color failures and the like based onthe photographed scene, correction amount is calculated on the basis ofthe photometric values of the second sensor, and exposure amount iscontrolled by setting as an exposure control value a value in which thiscorrection value is added to the basic exposure amount. A method ofcalculating correction amount and a method of controlling exposureamount are disclosed in detail in Japanese Patent Laid-Open Nos.311241/1988 and 311242/1988.

Although in the above a description has been given of the example inwhich the sensitivity of the sensor is changed differently for the shortwave range and the long wave range, an arrangement may be alternativelyprovided such that, in relation to the average sensitivity to the400-500 nm wavelength band, the average sensitivity to the 500 -600 nmwavelength band is reduced to 50% or less, and the average sensitivityto the 600-750 nm wavelength band is reduced to 20% or less. In thiscase, the magnitude of respective spectral photometric values in a casewhere the film is absent becomes approximately the same. Specifically, afilter with a transmittance of 50-20% is superposed on an interferencefilter with respect to the wavelength band of 500-600 nm, and a filterwith a transmittance of 25-5% is superposed on it with respect to thewavelength band of 600-750 nm. In addition, as another method, inrelation to the pixel area for the 400-500 nm band, the pixel area forthe 500-600 nm band may be reduced to 1/2 to 1/5, and the pixel area forthe 600-750 nm band to 1/4 to 1/20.

What is claimed is:
 1. An exposure controlling apparatus comprising:asensor for effecting photometry by separating light from an originalpicture into a plurality of separated components; storage means forstoring a value characteristic of the spectral sensitivity of saidsensor and a value characteristic of the spectral sensitivity of asensitive material to which an image is copied thereon; estimating meansfor estimating a spectral characteristic of the original picture on thebasis of a photometric value of said sensor and the value characteristicof the spectral sensitivity of said sensor stored in said storage means;and controlling means for determining a synthetic value which isequivalent to a value measured by a sensor having a spectral sensitivitydistribution identical with or similar to a spectral sensitivitydistribution of the sensitive material on the basis of the spectralcharacteristics of the original picture estimated and the valuecharacteristic of the spectral sensitivity of the sensitive material,and for controlling exposure amount on the basis of the synthetic value.2. An exposure controlling apparatus according to claim 1, whereinadjacent ones of said plurality of separated components have wavelengthbands which overlap each other.
 3. An exposure controlling apparatusaccording to claim 1, wherein said sensor has a wedge-shaped or steppedinterference filter which is provided with an interference film disposedon a transparent substrate and having varying thicknesses at differentpositions thereof, said interference filter being adapted to separatethe light from the original picture into a multiplicity of separatedcomponents.
 4. An exposure controlling apparatus according to claim 1,wherein said sensor is arranged to effect photometry by separating awavelength band corresponding to a maximum sensitivity wavelength bandof the sensitive material into a plurality of separated components. 5.An exposure controlling apparatus comprising:a sensor for effectingphotometry by separating light from an original picture into a pluralityof separated components; storage means for storing peculiar valuesobtained by integrating spectral sensitivity distributions of saidsensor corresponding to the respective separated components over veryfine wavelength sections including a central wavelength of each of theseparated components, and spectral sensitivities of a sensitive materialcorresponding to the very small wavelength sections; estimating meansfor estimating spectral characteristics of the original picturecorresponding to the respective very small wavelength sections on thebasis of photometric values of said sensor corresponding to therespective separated components and the peculiar values stored in saidstorage means; and controlling means for determining a synthetic valuewhich is equivalent to a value measured by a sensor having a spectralsensitivity distribution identical with or similar to a spectralsensitivity distribution of the sensitive material by integrating theproduct of the respective spectral characteristics of original pictureestimated and the respective spectral sensitivities of the sensitivematerial, and for controlling exposure amount on the basis of thesynthetic value.
 6. An exposure controlling apparatus comprising:a firstsensor for effecting photometry by separating light from an originalpicture into a multiplicity of spectral components, said first sensorincluding an interference filter which is provided with an interferencefilm disposed on a transparent substrate and having varying thicknessesat different positions thereof, the interference filter being adapted toseparate the light from the original picture into the multiplicity ofcomponents having central wavelengths corresponding to the thicknessesof said interference film; a second sensor for photometrically measuringred, green, and blue light by dividing the original picture into amultiplicity of fragments; and controlling means for determining a basicexposure amount on the basis of a synthetic value determined at leastfrom spectral photometric values of said first sensor, and forcontrolling an exposure amount on the basis of the basic exposureamount.
 7. An exposure controlling apparatus according to claim 6,wherein said controlling means determines the basic exposure amount onthe basis of the synthetic value determined from the spectralphotometric values of said first sensor, or determines the basicexposure amount on the basis of a color control value determined on thebasis of the synthetic value determined from the spectral photometricvalues of said first sensor and of a density control value determined onthe basis of photometric values of said second sensor, and controls theexposure amount on the basis of the basic exposure amount.
 8. Anexposure controlling apparatus according to claim 7, wherein saidcontrolling means further determines a correction value corresponding tothe contents of an image of the original picture on the basis of thephotometric values of said second sensor, and controls the exposureamount by means of a value in which the basic exposure amount iscorrected by the correction value.
 9. An exposure controlling apparatusaccording to claim 6, wherein said first sensor is provided with atransmitted light quantity controlling layer, or a pixel area of saidfirst sensor is changed, whereby the sensitivity of said first sensorwith respect to a long wave band is lowered relative to its sensitivityto a short wave band.
 10. An exposure controlling apparatus according toclaim 9, wherein said first sensor lowers its sensitivity with respectto a 500-600 nm wavelength band to 1/2 to 1/5, and its sensitivity withrespect to a 600-750 nm wavelength band to 1/4 to 1/20.
 11. An exposurecontrolling apparatus comprising:a first sensor for effecting photometryby separating light from an original picture into a multiplicity ofspectral components or a multiplicity of separated components andadapted to output a multiplicity of first photometric valuescorresponding to the multiplicity of spectral components and themultiplicity of separated components; a second sensor having maximumsensitivities in wavelength bands corresponding to three sensitivitybands of a sensitive material, and effecting photometry by dividing theoriginal picture into a multiplicity of fragments, said second sensorbeing adapted to output a multiplicity of second photometric valuescorresponding the multiplicity of fragments; first calculating means forcalculating a first average image density synthesized by adding weightto each of the multiplicity of first photometric values; secondcalculating means for calculating a second average image density byaveraging the multiplicity of second photometric values; thirdcalculating means for calculating a third average image density byaveraging the second photometric values belonging to a region whosecolor ratio or color difference from a reference value on predeterminedcolor coordinates is small; and controlling means for calculating anexposure amount control value on the basis of the first average imagedensity, the second average image density, and the third average imagedensity, and for controlling the exposure amount on the basis of theexposure amount control value.
 12. An exposure controlling apparatusaccording to claim 11, wherein said first calculating means calculatesthe basic exposure value on the basis of the first average image densityobtained by integrating or totalizing k.sub.λ ·SP.sub.λ ·d.sub.λ over apredetermined wavelength band where SP.sub.λ is a first photometricvalue at a wavelength λ of one of the spectral components or one of theseparated components, k.sub.λ is weight at the wavelength λ to be addedto the first photometric value, and d.sub.λ is a wavelength width of oneof the spectral components or one of the separated components.
 13. Anexposure controlling apparatus according to claim 11, wherein the secondaverage image density is a density determined from an arithmetic averagevalue of the multiplicity of second photometric values.
 14. An exposurecontrolling apparatus according to claim 11, wherein if it is assumedthat the first average image density is PDlj, the second average imagedensity is PD2j, and the third average image density is PD3j, saidexposure controlling means calculates the exposure amount control valuein accordance with PDlj+F·f(PD3j, PD2j) where j is 1 to 3, respectivelyrepresenting the three sensitivity wavelength bands of the copyingsensitive material, F is a constant or a value expressed by a constant,and f(PD3j, PD2j) is a functional expression comprising the thirdaverage image density PD3j and the second average image density PD2j.15. An exposure controlling apparatus according to claim 14, wherein##EQU17##
 16. An exposure controlling apparatus comprising:a firstsensor for photometrically measuring an original picture by separating awavelength band, corresponding to a maximum sensitivity wavelength bandof a sensitive material for copying an image of the original picturethereon, into a multiplicity of separated components; a second sensorfor photometrically measuring red, green, and blue light by dividing theoriginal picture into a multiplicity of fragments; calculating means forcalculating a synthetic value which is equivalent to a value measured bya sensor having a spectral sensitivity distribution identical with orsimilar to a spectral sensitivity distribution of the copying sensitivematerial for copying by adding weight to photometric values of saidfirst sensor; and controlling means for calculating a basic exposureamount on the basis of the synthetic value determined by saidcalculating means, or determining the basic exposure amount on the basisof a color control value determined from the synthetic value determinedby said calculating means and also on the basis of a density controlvalue determined from photometric values of said second sensor, and forcontrolling an exposure amount on the basis of the basic exposureamount.
 17. An exposure controlling apparatus according to claim 16,wherein the wavelength band corresponding to the maximum sensitivitywavelength band includes a 450-485 nm wavelength band, a 540-560 nmwavelength band, and a 680-710 nm wavelength band.
 18. An exposurecontrolling apparatus according to claim 16, wherein said first sensorcomprises a filter on which an interference film for separating awavelength band corresponding to at least one maximum sensitivitywavelength band into a plurality of separated components is deposited atdifferent positions in an identical plane.
 19. An exposure controllingapparatus according to claim 16, wherein said first sensor comprises afilter on which are deposited a first interference film for separating awavelength band corresponding to a maximum sensitivity wavelength bandinto a plurality of separated components and a second interference filmfor separating a wavelength band other than the wavelength bandcorresponding to the maximum sensitivity wavelength band into aplurality of separated components having a half-width wider than that ofsaid first interference film.
 20. An exposure controlling apparatusaccording to claim 16, wherein said first sensor comprises a filter onwhich are deposited a first interference film for separating awavelength band corresponding to a maximum sensitivity wavelength bandinto a plurality of separated components at at intervals of a narrowwavelength and a second interference film for separating a wavelengthband other than the wavelength band corresponding to the maximumsensitivity wavelength band into a plurality of separated components atintervals of a wider wavelength than said intervals of said wavelength.21. An exposure controlling apparatus according to claim 16, whereinsaid first sensor comprises interference films or filters, disposed atpositions where said interference films or said filters are not adjacentto each other, for separating a wavelength band corresponding to amaximum wavelength band into a plurality of separated components.